Stainless copper base alloy



Patented Dec. 4, 1934 ATENT QFFICE No Drawing. 1 Application my :1 i933,

IZCIaiIIB.

My invention, which relates to stainless copper base alloys, and hm among its objects the production of alloys of thiskind which may be readily worked into sheets and other forms by usual mill 5 processes, be best understood from the following description ofseveral examples of the alloy compoundedaccor'ding to the invention, the scope of which latter be'more particularly pointed out in the appended claims.

Heretofore copper base alloys containing nickel and chromium have been employed'in practice only for castings. For economic reasons it has been impractical to roll or otherwise mechanical- 1y work such prior alloys as they are brittle, diilicult to work cold, and next to impossible to work hot.

Applicant. has found that workable stainless copper base alloys can be produced by compounding copper, nickel and chromium in proper proportions particularly when suitable precautions are taken to secure solution of the chromium and to prevent deleterious secondary compounds,

alloysmay be readily cold and hot rolled into sheets and may be otherwise attenuated while cold or hot by usual .mill processes to produce various shapes.

The alloy may be compounded with or without zinc, but preferably with it except as hereinafter mentioned, as its presence it has been found fa.- cilitates the working of the alloy particularly when it is-to be annealed between the attenuating steps in the mill processes. Further, the alloypreferably is compounded with an additional constituent or constituents, hereinafter for convenience in terminology referred to as chromium incorporators, which will insure protecting the chromium from oxidation and insure its solution, and preferably also insure eliminating the effect onthe nickel of any. sulphur that may be present. In the absence of protecting the chromium from oxidation, the chromium when melted in or with cupro nickel is liable to come off as a slag or be in the form of an oxide distributed throughout the alloy, and if amounts of sulphur are present and are allowed to combine with the nickel the resulting nickel-sulphid may seriously interfere with the facility with which the alloy may be worked. It has been found that manganese will insure the solution of the chromium in the copper base alloy, as manganese has a greater a'mnity thanchromium for oxygen and a greater aflinity than nickel for sulphur, any possibility of oxidation of the chromium and formation of nickel-:Slflphid is'prevented effectively by use of this metal. The manganese-aflphid has (o1; is-n 1 no appreciable effect upon the workability of the alloy, and any execs of manganese, over that necessary tosecure these results within the ra of metals hereinafter stated, enters into solution and augments the effect of the nickel as a whitener for the alloy. I 7

As a substitute for manganese asa'so-called chromium incorporator, small amountsof magnesium and tin may be employed- The magnesium will prevent any pomibility of oxidation of the chromium and formation of nickel-sulphid,

while the tin will insure the solution of the chromium. In employing. m agnesium .precaution should be taken not to employ an amount thereof materially in excess ofthat necessary to take up the oxygen and sulphur, small amounts of magnesium in excess of this, say in the order of 0.25% uncombined metal, deleteriously. affecting the physical properties of the alloy within the ranges of metals hereinstated. When magnesium with tin is employed as a substitute for manganese the zinc may be omitted, and in practice ordinarily is. When desired the tensile strength of the alloy may be increased and controlled by addition of small amounts of vanadium, say from traces upv so to 0.1%, this metal also much improving the cold working properties of the alloy and its ductility and elongation. i

The amount of nickel may be varied to vary the color of the alloy. -With a' high nickel content of about 18% a bright, clear white 'metal characteristic of the color of stainless steel is secured. By decreasing the nickel content to 10% and below alloys of warmer tones are obtained, with a suggestion of a rose or. pinkish tint underlying the white, which warmer tones are desirable for architectural work. The nickel content should ordinarily not exceed approximately from 20 to 22%, as abo'vethese values the alloy becomes increasingly diflicult to work. On the other hand, the nickel content should not ordinarily be less than approximately from 4 to 5%, as below these values the alloy loses its characteristic color and ceases to-be stainlessl t The copper conta'ntfshould be relativ y h, and ordinarily not less than approximately 65%Q of the alloy, as with lower copper values the alloy becomes increasingly brittle and difficult to work. Further, the copper content should not exceed approximately 90% when zinc and manganese are employed, or exceed approximately 93% when zinc is omitted and magnesium with tin is employed as asubstitute for manganese.

Further, to secure the desirable properties of the alloy within the ranges of other constituents hereinafter mentioned, the sum of the copper and nickel should not be less than approximately 80%, or when zinc is present exceed approximately 95%, or in the absence of mately 97%.

It has been found that the amount of chromium ordinarily should not exceed approximately 5% as values in excess of this make the alloy difficult to work, and ordinarily should not be less than approximately 0.5% to insure that the alloy is stainless. It has further been found, that to secure the desirable properties of the alloy within this range of chromium, the amount thereof should vary approximately linearly and inversely with the amount of copper, satisfactory results ordinarily being secured when the amount of chromium is within plus or minus 25% of the value determined by this ratio, so long as it is not materially above the maximum or below the minimum values thereof of 5 and 0.5% respectively.

It has been found that under ordinary conditions amounts of manganese less than 0.25% will not insure satisfactory results, and that amounts in excess of 5% are likely to cause the alloy to become brittle -and refractory with the range of' chromium above stated. Further, to secure best results, the amount of manganese should vary approximately linearly and directly with the amount of chromium, it ordinarily being satisfactory when the amount of manganese is within plus or minus 25% of the value determined by this ratio. When magnesium with tin is employed as a substitute for manganese, to prevent the presence of a deleterious excess of magnesium, over that necessary to prevent both oxidation of the chromium and formation'of deleterious amounts of nickel-sulphid, the amount of magnesium should ordinarily not exceed approximately 5%, and, to insure satisfactory effects, should ordinarily not be less than approximately 0.25%, while within the range of chromium above stated the amount of tin should not exceed approximately 0.5% or be less than approximately 0.1%. To secure best results, the specific amounts of magnesium and tin should, like the manganese, ordinarily vary approximately linearly and directly with the-amount of chromium, satisfactory results ordinarily being secured when the amounts of magnesium and tin are within plus or minus'25% of the value determined by this ratio.

As hereinbefore mentioned, the zinc, which preferably is employed, particularly when manganese is used to facilitate incorporation of the chromium, should not exceed approximately 20% of the alloy, as zinc values in excess of this tend to make the alloy brittle.

The general approximate formula for the basic copper, nickel, chromium alloys may be stated as copper 65 to 93 parts/nickel 4,to 22 parts, and

chromium 0.5 to 5 parts, with the sum of the copper and nickel between and 97 parts. When zinc is added to these basic alloys, the general approximate formula becomes copper 65 to 93 parts, nickel 4 to 22 parts, chromium 0.5 to 5 parts, and zinc the balance to make 100 parts, with the sum of the copper and nickel as before; and if the alloys contain vanadium the same may be substituted for an equal part of the zinc. When a chromium incorporator is employed with these basic copper, nickel, chromium alloys, 0.25 to 5 parts manganese (or 0.25 to 5 parts magnesium plus 0.1 to 0.5 parts tin) may be employed. When both zinc and the chromium incorporator are employed with these basic copper, nickel, chrozinc exceed approxi in the range thereof stated preferably should vary approximately linearly and inversely with the amount of copper, and the manganese, magnesium and tin within the ranges thereof stated preferably should vary approximately linearly and directly with the amount of chromium.

As suitable alloys for fabricating sheets for architectural purposes, the following give satisfactory results:

. Per cent Copper 75 Nickel 18 Chromium i 0.5 to 1 Zinc balance or the above alloys containing from 0.5 to 1% manganese substituted for an equal amount of the vzinc, and in either case, if desired, small amounts of vanadium in the orderof 0.01%.

As suitable alloys for fabricating sheets for automobile headlights, radiators, and the like, the following give satisfactory results:

Per cent Copper 68 Nickel 19 Chromium -2. 3 to 3.5 Manganese 4 Vanadium 0.02 to 0.03 Zinc balance It has been found that excellent alloys satisfactory for ordinary purposes can be compounded according to the invention consisting of As a suitable method of compounding the above alloys the copper and nickel may be melted together and the temperature of the melt raised to about 2300 F. The manganese may then be added in the form of a copper alloy rich in manganese, say one containing 25% manganese. The chromium may be added in the form of a copper alloy rich in chromium, say one containing 10% chromium, and then the vanadium may be added in the same way. The zinc may be added in the form of brass to cool the. melt to about 2000'" F. just before pouring. When the alloy contains tin the same may be added to the molten copper-and nickel in the form of bronze scrap, after which the magnesium and chromium may be added, in

other metals than those herein mentioned may be added to the alloy to give it special characteristics when they do not to a material extent change the hereinbefore mentioned desirable physical and chemical properties of the alloy, and also that wide deviations maybe made from the embodiments of the invention herein dewithout departing from the spirit of the invention.

I claim:

1. Stainless hot and cold workable so-called white metal alloys.containing copper, nickel, chromium, manganese and zinc, the copper, nickel, chromium and manganese being within 'the'following approximate ranges: copper to 90%, nickel 5 to 22%, chromium 0.5 to 5%. and manganese 0.25 to 5%; inall the sum of the copper and nickel being between approximately and'95% and a substantial amount/of zinc being present, the zinc constituting substantially the balance of the alloy in respect to the other metals mentioned.

2. Stainless hot and cold workable so-called white metal alloys containing copper, nickel, chromium, manganese and zinc, the copper, nickel, chromium and manganese being within the following approximate ranges: copper 65 to nickel 5 to 22%, chromium 0.5 to'5%, and manganese 0.25 to 5%; the percentage amount of chromium being roughly linearly and inversely proportional to the percentage amount of copper within said ranges of chromium and copper; in all instances thesum of the copper and nickel being between approximately 80 and %.and a substantial amount of zinc being present, the

zinc constituting substantially the balance of me alloy in respect to the other metals mentioned.

3. Stainless hot and cold workable so-called white metal alloys containing copper, nickel,

chromium, manganese and zinc, the copper,

nickel, chromium and being within the following approximate ranges: copper to 90%,nickel 5 to 22%, chromium 0.5 to 5%, and manganese 0.25 to 5%; the percentage amount of manganese being roughly linearly and directly proportional to the percentage mom of chromium within said ranges Of m n nese and chromium;inallinstancesthesumofthecopper and nickel being between approximately 80 and 95% and a substantial amount of zinc being present, the zinc constituting substantially the balance of the alloy in'respect to the other metals mentioned.

4. Stainless hot and cold workable so-called white metal alloys containing copper, nickel,

manganese and zinc, the copper,

nickel, chromium and manganese being within the following approximate rames: copper 65 to 90%, nickel 5 to 22%. chromium 0.5 to 5%, and

manganese 0.25 to 5%; the percentage amount of chromium being roughly linearly and inverse- 1y proportional to thepercentage amount of copper within said ranges of chromium and copper, the percentage amount of manganese being roughly linearly and directly'proportional to the percentage amount of chromium within said ranges of manganese and chromium; in all instances the sum of the copper and nickel being betwwn approximately 80 and 95% and asubstantial amount of zinc being present, the zinc constituting substantially the balance of the alloy in respect to the other metals mentioned.

5. Stainles hot and cold workable so-called white metal alloys containing, approximately, copper 68%, nickel 19%, chromium 3 to 3.5%. "211? 4%, the balm all zinc.

5. Stainless hot and cold workable so-called white metal alloys containing, approximately, copper 75%, nickel 18%, chromium 6.5m 1%. 0.5to1%,thebalancesubstantially 7. The alloys according to claim 1 containing ,fromatraceto0.l% vanadium.

1:.1healloysaccordingtoclaim5containing tromatracetoill'k vanadium RICHARDLWILKINS. 

